Why is my chain not always catching on large chain wheel

Hey just replaced my Shimano 6500 rear derailleur with a 105 10speed one, and have replaced the chain to a 9speed one. Plz why does the front chain wheel not always catch.

My bike is 9 speeds (read online a 10 speed deraileeur would work.

Plzzz help :)

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Chainring looks worn out to me... Chain shouldn't be off the chain ring like that

Need to adjust the cable of front mech and try to play those two screws

Your lax attitude to bike cleaning has come back to bite you on the arse?

@andyfallsoff it was working fine before my de-raileur snapped though and I had to replace it,

@AlphaOmega will give that a go thanks!

@andyp is there really any point in cleaning a commuting bike in London?

is there really any point in cleaning a commuting bike in London?

Not just riding it, they need a care too so they'll last longer

You asked...

Your old chain was probably worn a similar amount to the chainring, so they worked together. A new chain on and old, worn chainring will do exactly what your picture shows, so I think you're going to need a new chainring or two. If you've gone as far as a new chain and chainrings (as well as derailleur), then it's probably also worth checking the cassette and maybe replacing that - then you'd have a new and reliable entire drivetrain.

Then replace your chain again in however many miles (wild guess, people have different opinions, maybe in 2000 miles?)

and

by now you may need a new chain again too

You're quick! Pressed send too early...